with baseline (i.e. no microinjection) days between infusions. In all cases where microinjections were delivered, injection volume was 0.1 μl per side delivered over 30 sec. In some animals, OxoSQ had sufficient suppressive effects on lever pressing to result in BPs being reached within 70 min of the start of the session; in some animals no lever pressing occurred. This was the case for 4 of the 12 animals after infusion with the 1nmol dose and for 6 of the 12 animals after infusion with the 10nmol dose. For animals that failed to press the active lever, or reached a BP of only FR-1 or FR-2, sessions were immediately restarted on the PR schedule for another 180 min. This practice was followed to show that these animals would lever press once the drug effects from the microinjection had dissipated. The infusions for restarted sessions were accumulated in time bins 90 min and beyond. For most treatments, animals had at least two baseline sessions before receiving the next treatment. Some animals, however, had only one baseline session before treatment if the baseline session did not change in BP from the previous baseline session. To determine whether the effect of OxoSQ was
